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SubjectRe: [PATCH v3 1/5] memblock: Introduce allocation direction to memblock.
Hello tejun,

On 09/23/2013 11:38 PM, Tejun Heo wrote:
> Hello,
>
> Sorry about the delay. Was traveling.

hoho~ I guess you did have a good time.

>
> On Fri, Sep 13, 2013 at 05:30:51PM +0800, Tang Chen wrote:
>> +/* Allocation order. */
>> +#define MEMBLOCK_DIRECTION_HIGH_TO_LOW 0
>> +#define MEMBLOCK_DIRECTION_LOW_TO_HIGH 1
>> +#define MEMBLOCK_DIRECTION_DEFAULT MEMBLOCK_DIRECTION_HIGH_TO_LOW
>
> Can we please settle on either top_down/bottom_up or
> high_to_low/low_to_high? The two seem to be used interchangeably in
> the patch series. Also, it'd be more customary to use enum for things
> like above, but more on the interface below.

OK. let's use top_down/bottom_up. And using enum is also ok.

>
>> +static inline bool memblock_direction_bottom_up(void)
>> +{
>> + return memblock.current_direction == MEMBLOCK_DIRECTION_LOW_TO_HIGH;
>> +}
>
> Maybe just memblock_bottom_up() would be enough?

Agreed.

>
> Also, why not also have memblock_set_bottom_up(bool enable) as the
> 'set' interface?

hmmm, ok. So we will use memblock_set_bottom_up to replace
memblock_set_current_direction below.

>
>> /**
>> + * memblock_set_current_direction - Set current allocation direction to allow
>> + * allocating memory from higher to lower
>> + * address or from lower to higher address
>> + *
>> + * @direction: In which order to allocate memory. Could be
>> + * MEMBLOCK_DIRECTION_{HIGH_TO_LOW|LOW_TO_HIGH}
>> + */
>> +void memblock_set_current_direction(int direction);
>
> Function comments should go with the function definition. Dunno what
> happened with set_current_limit but let's please not spread it.
>
>> +void __init_memblock memblock_set_current_direction(int direction)
>> +{
>> + if (direction != MEMBLOCK_DIRECTION_HIGH_TO_LOW &&
>> + direction != MEMBLOCK_DIRECTION_LOW_TO_HIGH) {
>> + pr_warn("memblock: Failed to set allocation order. "
>> + "Invalid order type: %d\n", direction);
>> + return;
>> + }
>> +
>> + memblock.current_direction = direction;
>> +}
>
> If set_bottom_up() style interface is used, the above will be a lot
> simpler, right? Also, it's kinda weird to have two separate patches
> to introduce the flag and actually implement bottom up allocation.

Yeah, right, that'd be much simpler. And it is ok to put the two in
one patch.

Thanks.

>
> Thanks.
>


--
Thanks.
Zhang Yanfei


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